The invention relates to a semiconductor device, in particular a semiconductor device capable of communicating data wirelessly.
A semiconductor device capable of communicating data wirelessly is typified by a wireless chip. A wireless chip is used for production management by assigning an identification number (ID) to an object and storing the history thereof. A wireless chip assigned an ID (wireless tag) is also used for utilization and management of personal data, money and the like. Such a wireless chip is called an ID tag, an IC card or the like, and has been manufactured in quantity and widely used with development of identification technology and increase in demand.
Depending on the application, a wireless chip is changed in communication distance, communication method, size, the presence or absence of an internal power supply, configuration of an internal memory, and the like, For production management, demand for a small and lightweight wireless tag with a long communication distance has increased.
A wireless tag that has no internal power supply and operates with externally supplied power can be reduced in size and weight; however, the communication distance depends largely on circumstances, and in particular the presence or absence of a conductor around an antenna.
Since a wireless chip communicates data wirelessly, it involves a risk of interception of data and forgery of data. In addition, important data such as money or personal privacy is stored in a wireless chip in some cases, and it is thus necessary to improve the security of the stored data.
Accordingly, if a wireless chip incorporates a rewritable memory, some measures such as cryptographic security technology are required.
In order to prevent forgery of data, a memory (write-once memory) that can be written only once and cannot be rewritten may be incorporated.
In the case of incorporating a write-once memory, a wireless chip preferably incorporates a memory where data can be written after the production, particularly in the initial use rather than a memory such as a mask ROM where data can be written only during the production. As a result, an easy-to-use and high demand wireless chip can be achieved.
The frequency of use of the wireless chip has increased each year, and the wireless chip is required to be manufactured at lower cost.
In order to supply a wireless chip meeting users' demand, it is necessary to provide a small and lightweight wireless chip with a long communication distance, high security of data, and high usability, which can be manufactured at a low cost using an inexpensive material and a simple structure.
Many of wireless chips that have been put into practical use have a circuit (also called an IC: Integrated Circuit chip) using a semiconductor substrate such as a Si substrate as well as an antenna. The IC chip is constituted by a memory circuit (also called a memory), a control circuit and the like. These semiconductor devices are required to be manufactured at a low cost; therefore, in recent years, an organic TFT, an organic memory and the like, which use an organic compound for a control circuit, a memory circuit and the like, have been actively developed (see Japanese Patent Laid-Open No. 2004-47791 for example).